[IOT-1330] Fixed build error caused by calling tinydtls build script twice

[IOT-1330] Fixed build error caused by calling tinydtls build script twice

When building android build with SECURED=1 there is no need to call the tinydtls
build script it is build as part of the csdk.

See: resource/csdk/connectivity/src/SConscript line 60

Change-Id: Idf140944f81ca33369a42f2986e526b38882a3f5
Signed-off-by: George Nash <george.nash@intel.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/12673
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Herman Lu <herman.ghlu@gmail.com>
Reviewed-by: Larry Sachs <larry.j.sachs@intel.com>
Reviewed-by: Rick Bell <richard.s.bell@intel.com>